meat inspection is maintained. The information thus obtained is transmitted to the authorities of the various States from which the animals are shipped, and it is hoped that it will be used in endeavoring to locate the centers where infection exists and to eradicate the disease. When a system of cooperation can be effected between the State and Federal governments, providing for a general plan of tagging all dairy cows shipped to market centers for slaughter, then the work of locating these disease centers will be greatly simplified. Had the packers been successful in their recent efforts to buy all such cattle subject to inspection, such a system of tagging would have been necessary in order for the identity of the animal to be retained.

INTERSTATE QUARANTINE MAY BECOME NECESSARY.

It may at some time be necessary for the Federal Government to quarantine against the interstate shipment of cows from certain States where the disease prevails to a considerable extent and require a strict supervision over all animals removed from such States for interstate shipment, and only remove the quarantine from sections of a State when it has been demonstrated that the disease has been either eradicated or is under strict local quarantine.

CONCLUSION.

In my opinion the time is very near at hand when we must face the problem of eradicating this plague from the herds of the country. It is therefore well for veterinarians, stock raisers, sanitary officers, and others concerned to give the subject most careful thought and consideration, so that the problem may be dealt with in the most practical and effective way. It means the expenditure of millions of dollars of public money and a great financial loss to individuals. In a movement of this magnitude it is necessary to have the support of the public and of the live-stock owners in general in order to meet with success, and they should be informed as to the great danger of tuberculosis, both from the economic and health points of view. From either standpoint the eradication of the disease is highly desirable, and the advantage to be gained will, in my judgment, abundantly justify the heavy expense involved.

TUBERCULOSIS OF HOGS: ITS CAUSE AND SUPPRESSION.

BY JOHN R. MOHLER, A. M., V. M. D.,

Chief of the Pathological Division,

AND

HENRY J. WASHBURN, D. V. S.,

Assistant Chief of the Pathological Division.

INTRODUCTION.

Tuberculosis in the human family has been lessening materially during the past fifteen years, but reports from the various meat-packing centers of the country fail to show the same encouraging condition regarding tuberculosis in hogs during the same space of time. It must be admitted that reports have come from several localities during the past four years showing a decrease in the number of tuberculous swine sent to market, but a review of the collective records of the country at large shows an increase rather than a decrease in the number of swine affected. Indeed, there is probably no disease of hogs, not even excepting hog cholera, which is causing heavier losses to the hog raiser than tuberculosis, and it is also the cause of great loss to the packers and of much anxiety to the veterinary inspector of meats. Until recent years tuberculosis had been looked upon as of uncommon occurrence, and only of importance from a meat-inspection standpoint; but to-day it must be considered as a general veterinary problem, theoretically easy of solution, which should receive the careful attention of all sanitarians.

The swine of this country January 1, 1908, according to estimates of the Bureau of Statistics of the Department of Agriculture, numbered 56,084,000, and their value at that time was $339,030,000. From these figures one may partially realize the serious menace to the hog-raising industry which is offered by a disease which affects almost 1.5 per cent of all hogs slaughtered at the abattoirs of this country which have Federal inspection. Reports from European abattoirs show that tuberculosis is far more widespread among their hogs than among ours, some of the returns showing as high as 5.5 to 7.5 per cent. It is to be hoped that the spread of the disease in this country may be checked, and that concerted action by the stock owners and veterinarians may lead to the complete eradication of this costly affection.

The small amount of money required to begin hog raising and the quick returns on the capital invested make this industry an attractive one to the small farmer. The hog will make a pound of gain on less feed than most live stock, and will profitably utilize waste food products of every variety if properly prepared for him. As tuberculosis in this species is chiefly acquired by ingestion, the significance of the latter statement is obvious.

Tuberculosis of hogs is closely associated with the same malady in cattle. The reason for this is apparent when one considers the close relations of these two species of domestic animals upon nearly every farm. The Bureau of Animal Industry is at present endeavoring to locate infected farms, or at least infected localities, and to ascertain the direct cause of the spread of the disease in these districts. Owing to the number of hands through which hogs go before reaching the abattoirs this is not an easy proposition, but it can be and is being accomplished. Already through cooperation with the State authorities a large number of infected farms have been definitely located. The conditions on these farms have been investigated, the source of the disease determined, and methods for its suppression recommended. In Wisconsin the Bureau and State officials have been working with these ends in view. When hogs have been found to be tuberculous and the farm from which they came has been located, the State veterinarian is notified, and he is empowered by law to quarantine any farm when he suspects the presence of a contagious disease thereon. He then applies the tuberculin test to the cattle on the farm and otherwise looks for the source of infection. This frequently results in finding the cattle tuberculous. Similar cooperation has recently been taken up with Nebraska, Iowa, and Minnesota, and the results are equally encouraging.

This cooperation with the State is of great value, and the results would be of greater magnitude if State legislation could be secured compelling the tagging of all hogs going to slaughter, whereby these animals if found tuberculous could be immediately traced to their point of origin and the source of infection removed. It is evident that the suppression of hog tuberculosis would save the country millions of dollars annually, and when it is realized that there are vast numbers of tuberculous hogs killed in abattoirs having no inspection of any kind, it can be seen that the danger to human life from this source would at the same time be removed.

PREVALENCE OF THE DISEASE.

The prevalence of tuberculosis among swine must be judged from abattoir statistics entirely. Thus it has been noted from the records. kept by the Bureau of Animal Industry that some sections of the country contribute a far greater proportion of diseased animals than

others. Hogs from Arkansas, Oklahoma, and Texas are remarkably free from this disease, due probably to the method of caring for them, or rather the lack of caring for them. They are not hampered in feed lots as those are in the sections where the disease is mostly found, but are allowed to roam over large areas of pasture and to shift for themselves, and when they are found affected the majority of them show very slight lesions. Furthermore, no prolonged feeding is practiced in narrow bounds as in the corn belt. Lastly, there are relatively few dairies in these sections, and likewise few tuberculous cattle. On the other hand, the hogs are carried from birth to maturity on some form of pasture, as alfalfa, oats, corn, cowpeas, sorghum, rape, and peanuts all the year round. The hogs of the forest region of Hungary which are pasture fed are likewise rarely tuberculous, according to Hertwig, and there can be no doubt that swine fed on entirely vegetable food, as corn and roughage, are proportionately less affected than those fed on dairy products or behind diseased cattle.

A great many hogs in Texas are raised on alfalfa supplemented with corn, and the result is clearly shown in the Bureau statistics which indicate that from January 1 to June 30, 1907, only one-tenth of 1 per cent of over 325,000 hogs slaughtered at Fort Worth showed tuberculous lesions, while only 51, or 0.016 per cent, were condemned as unfit for food. In striking contrast to this may be given the percentages for the same period of three cities in one of the leading dairy States, which show 3.1 per cent, 3.4 per cent, and 6.4 per cent, respectively, of the hogs slaughtered to be affected with tuberculosis. There are a large number of cooperative creameries in the territory contiguous to the three cities alluded to, and the raw skimmed milk is taken home by the patrons for their hogs. Samples of separator slime from the two creameries in the town showing the largest number of tuberculous hogs were injected into guinea pigs and in one instance virulent tubercle bacilli were recovered.

The hog buyers for packing houses are from bitter experience gradually becoming familiar with these conditions and are avoiding certain sections of certain States, and there are at least two eastern packers who will not under any conditions kill hogs from one of the badly infected States. In other localities the packers are beginning to take self-protective measures so as to have the feeder of diseased hogs bear the burden, and many of the smaller establishments in the Central West are buying hogs subject to post-mortem inspection. This attack on the farmer's purse will probably have more beneficial results in making him fully alive to the seriousness of the situation than any other procedure.

In an endeavor to trace the origin of the infection of tuberculous hogs that were arriving at one of the packing plants of Iowa, Rogers of

the Bureau of Animal Industry for some time carried on an experiment which consisted in tagging the hogs that were hauled to market at that place in wagons, before they were removed from the farmers' wagons, and later using these tags as means of identification in case tuberculosis was found to exist in any of the hogs at the time of slaughter. In this manner 3,420 hogs were tagged, and on tracing them to their final disposal it was learned that all of the tuberculous live stock brought to that market came from a few farms-less than 6 per cent of the total, while the remaining 94 per cent of the farms were free from the disease. This proportion of noninfected farms should give great encouragement to any efforts that may be made to eradicate the disease from the State. It was further noted that the successive shipments of hogs marketed by certain farmers always contained tuberculous animals, and in at least two instances the entire consignments were condemned for tuberculosis at the time of slaughter.

PREVALENCE OF TUBERCULOSIS IN FOREIGN COUNTRIES.

Statistics of the sanitary inspection of the Federal slaughterhouses in the Argentine Republic show that the percentage of tuberculous swine is greater than that of tuberculous cattle. This fact is also true in this country, although the contrary is shown in the greater part of the European countries.

In the abattoirs of Buenos Aires the percentage of tuberculous swine for several years past was as follows:

In the abattoirs of Liniers at the above city the relation of the two forms of tuberculosis in swine is represented by the following figures:

Proportion of generalized and localized tuberculosis of hogs found at abattoirs of Liniers, Buenos Aires.